This Seminar has two talks.

Talk by Alessandra Stella:

Title: Multiple Overlapping Cell Assemblies Active During Motor Behavior

Abstract:  The cell assembly hypothesis postulates that information processing in the brain entails the repetitive co-activation of groups of neurons [1]. The activation of such assemblies would lead to spatio-temporal spike patterns (STPs) at the resolution of a few milliseconds. In order to test the cell assembly hypothesis, we searched for significant STPs in parallel spike trains, using the SPADE method [2,3]. We analyzed experimental data from the motor cortex (M1/PMd) of macaque monkeys (Macaca mulatta) performing a reach-to-grasp task [4] and found an abundance of STPs. Quantitative analysis showed that STPs are functionally related to behavior, which suggests the presence of assemblies activated during the task.

References:

[1] Hebb, D. O. (1949). John Wiley & Sons

[2] Stella et al. (2019). Biosystems, 185, 104022. [doi: https://doi.org/10.1016/j.biosystems.2019.104022]

[3] Stella et al. (2022). eNeuro [doi: https://doi.org/10.1523/ENEURO.0505-21.2022]

[4] Brochier et al. (2018). Scientific data 5.1: 1-23. [doi: https://doi.org/10.12751/g-node.f83565]

Talk by Aitor Morales-Gregorio:

Title: Feedback modulation of neural manifolds in macaque primary visual cortex

Abstract: High-dimensional brain activity is in many cases organized into lower-dimensional neural manifolds [1,2]. Feedback from V4 to V1 is known to mediate visual attention [3] and computational work has shown that it can also rotate neural manifolds in a context-dependent manner [4]. However, whether feedback signals can modulate neural manifolds in vivo remains to be ascertained. Here, we studied the neural manifolds in macaque (Macaca mulatta) visual cortex during resting state [5] and found two distinct high-dimensional clusters in the activity. The clusters were primarily correlated with behavioral state (eye closure) and had distinct dimensionality. Granger causality analysis revealed that feedback from V4 to V1 was significantly stronger during the eyes-open periods. Finally, spiking neuron model simulations confirmed that signals mimicking V4-to-V1 feedback can modulate neural manifolds. Taken together, the data analysis and simulations suggest that feedback signals actively modulate neural manifolds in the visual cortex of the macaque.

References:

[1] Stringer et al. (2020). Nature 571, 361-365. https://doi.org/10.1038/s41586-019-1346-5

[2] Singh et al. (2008). Journal of Vision 8(8), 11. https://doi.org/10.1167/8.8.11

[3] Poort et al. (2012). Neuron 75 (1), 143-156. https://doi.org/10.1016/j.neuron.2012.04.032

[4] Naumann et al. (2022). eLife 11, 76096. https://doi.org/10.7554/eLife.76096

[5] Chen*, Morales-Gregorio* et al. (2022). Scientific Data 9 (1), 77. https://doi.org/10.1038/s41597-022-01180-1